/***
 * Thanks http://mxl86.javaeye.com/blog/300128 for this v-code programme.
 *
 */
package tool;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;

public class RandomNumUtil
{

    private ByteArrayInputStream image;//图像
    private String str;//验证码
    private static String c = "abcdefghijklmnopqrstuvwxyz0123456789";

    private RandomNumUtil()
    {
        init();//初始化属性
    }
    /*
     * 取得RandomNumUtil实例
     */

    public static RandomNumUtil Instance()
    {
        return new RandomNumUtil();
    }
    /*
     * 取得验证码图片
     */

    public ByteArrayInputStream getImage()
    {
        return this.image;
    }
    /*
     * 取得图片的验证码
     */

    public String getString()
    {
        return this.str;
    }

    private void init()
    {
        // 在内存中创建图象
        int width = 60, height =23;
        BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        // 获取图形上下文
        Graphics g = img.getGraphics();
        // 生成随机类
        Random random = new Random();
        // 设定背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);
        // 设定字体
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
        // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
        g.setColor(getRandColor(160, 200));
        for (int i = 0; i < 155; i++)
        {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.drawLine(x, y, x + xl, y + yl);
        }
        // 取随机产生的认证码(6位数字)
        String sRand = "";
        for (int i = 0; i < 4; i++)
        {
            int rand = random.nextInt(36);
            sRand+= c.charAt(rand)+"";
            // 将认证码显示到图象中
            g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
            // 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
            g.drawString(c.charAt(rand)+"", 13 * i + 6, 16);
        }
        //赋值验证码
        this.str = sRand;

        //图象生效
        g.dispose();
        ByteArrayInputStream input = null;
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        try
        {
            ImageOutputStream imageOut = ImageIO.createImageOutputStream(output);
            ImageIO.write(img, "JPEG", imageOut);
            imageOut.close();
            input = new ByteArrayInputStream(output.toByteArray());
        } catch (Exception e)
        {
            System.out.println("验证码图片产生出现错误：" + e.toString());
        }
        finally
        {
            try
            {
                output.close();
                input.close();
            }catch(Exception e){}
        }
        
        this.image = input;/* 赋值图像 */
    }
    /*
     * 给定范围获得随机颜色
     */

    private Color getRandColor(int fc, int bc)
    {
        Random random = new Random();
        if (fc > 255)
        {
            fc = 255;
        }
        if (bc > 255)
        {
            bc = 255;
        }
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }
}